Are Humans Too Generous and Too Punitive? Using Psychological Principles to Further Debates about Human Social Evolution

Are humans too generous and too punitive? Many researchers have concluded that classic theories of social evolution (e.g., direct reciprocity, reputation) are not sufficient to explain human cooperation; instead, group selection theories are needed. We think such a move is premature. The leap to these models has been made by moving directly from thinking about selection pressures to predicting patterns of behavior and ignoring the intervening layer of evolved psychology that must mediate this connection. In real world environments, information processing is a non-trivial problem and details of the ecology can dramatically constrain potential solutions, often enabling particular heuristics to be efficient and effective. We argue that making the intervening layer of psychology explicit resolves decades-old mysteries in the evolution of cooperation and punishment

The Importance of Being Honest?

Deceiving participants about the goals or content of a study is permitted in psychological research but is banned in economics journals and subject pools. This ban is intended to protect a public good: if experiencing deception causes participants to be suspicious in future studies, and suspicion influences their behavior, then the entire field suffers. We report a survey on psychologists and economists’ attitudes towards deception (N=568), and a large, non-deceptive multi-site study in which we measured participants’ histories, suspicion levels, and behavior in four common economic tasks (N=636). Economists reported wide ranging negative attitudes towards deceptive methods and support for the deception ban. However, the results of the behavioral study undercut the rationale of the deception ban: participants’ present suspicion unrelated to past experiences of deception, and suspicious participants behaved identically to credulous participants. We conclude that banning deceptive methods cannot be justified as the protection of a public good

Welfare tradeoff psychology is present in children and adults

Making decisions in a social context often requires weighing one's own wants against the needs and preferences of others. Adults are adept at incorporating multiple contextual features when deciding how to trade off their welfare against another. For example, they are more willing to forgo a resource to benefit friends over strangers (a feature of the individual) or when the opportunity cost of giving up the resource is low (a feature of the situation). When does this capacity emerge in development? In Experiment 1 (N = 208), we assessed the decisions of 4- to 10-year-old children in a picture-based resource tradeoff task to test two questions: (1) When making repeated decisions to either benefit themselves or benefit another person, are children’s choices internally consistent with a particular valuation of that individual? (2) Do children value friends more highly than strangers and enemies? We find that children demonstrate consistent person-specific welfare valuations and value friends more highly than strangers and enemies. In Experiment 2 (N = 200), we tested adults using the same pictorial method. The pattern of results successfully replicated, but adults’ decisions were more consistent than children’s and they expressed more extreme valuations: relative to the children, they valued friends more and valued enemies less. We conclude that despite children’s limited experience allocating resources and navigating complex social networks, they behave like adults in that they reference a stable person-specific valuation when deciding whether to benefit themselves or another and that this rule is modulated by the child’s relationship with the target

What Are Punishment and Reputation for?

Why did punishment and the use of reputation evolve in humans? According to one family of theories, they evolved to support the maintenance of cooperative group norms; according to another, they evolved to enhance personal gains from cooperation. Current behavioral data are consistent with both hypotheses (and both selection pressures could have shaped human cooperative psychology). However, these hypotheses lead to sharply divergent behavioral predictions in circumstances that have not yet been tested. Here we report results testing these rival predictions. In every test where social exchange theory and group norm maintenance theory made different predictions, subject behavior violated the predictions of group norm maintenance theory and matched those of social exchange theory. Subjects do not direct punishment toward those with reputations for norm violation per se; instead, they use reputation self-beneficially, as a cue to lower the risk that they personally will experience losses from defection. More tellingly, subjects direct their cooperative efforts preferentially towards defectors they have punished and away from those they haven’t punished; they avoid expending punitive effort on reforming defectors who only pose a risk to others. These results are not consistent with the hypothesis that the psychology of punishment evolved to uphold group norms. The circumstances in which punishment is deployed and withheld–its circuit logic–support the hypothesis that it is generated by psychological mechanisms that evolved t

Welfare tradeoff psychology is present in children and adults

Making decisions in a social context often requires weighing one's own wants against the needs and preferences of others. Adults are adept at incorporating multiple contextual features when deciding how to trade off their welfare against another. For example, they are more willing to forgo a resource to benefit friends over strangers (a feature of the individual) or when the opportunity cost of giving up the resource is low (a feature of the situation). When does this capacity emerge in development? In Experiment 1 (N = 208), we assessed the decisions of 4- to 10-year-old children in a picture-based resource tradeoff task to test two questions: (1) When making repeated decisions to either benefit themselves or benefit another person, are children’s choices internally consistent with a particular valuation of that individual? (2) Do children value friends more highly than strangers and enemies? We find that children demonstrate consistent person-specific welfare valuations and value friends more highly than strangers and enemies. In Experiment 2 (N = 200), we tested adults using the same pictorial method. The pattern of results successfully replicated, but adults’ decisions were more consistent than children’s and they expressed more extreme valuations: relative to the children, they valued friends more and valued enemies less. We conclude that despite children’s limited experience allocating resources and navigating complex social networks, they behave like adults in that they reference a stable person-specific valuation when deciding whether to benefit themselves or another and that this rule is modulated by the child’s relationship with the target

Spatial adaptations for plant foraging: women excel and calories count

We present evidence for an evolved sexually dimorphic adaptation that activates spatial memory and navigation skills in response to fruits, vegetables and other traditionally gatherable sessile food resources. In spite of extensive evidence for a male advantage on a wide variety of navigational tasks, we demonstrate that a simple but ecologically important shift in content can reverse this sex difference. This effect is predicted by and consistent with the theory that a sexual division in ancestral foraging labour selected for gathering-specific spatial mechanisms, some of which are sexually differentiated. The hypothesis that gathering-specific spatial adaptations exist in the human mind is further supported by our finding that spatial memory is preferentially engaged for resources with higher nutritional quality (e.g. caloric density). This result strongly suggests that the underlying mechanisms evolved in part as adaptations for efficient foraging. Together, these results demonstrate that human spatial cognition is content sensitive, domain specific and designed by natural selection to mesh with important regularities of the ancestral world

Genomic imprinting is implicated in the psychology of music

Why do we sing to babies? Human infants are relatively altricial and need their parents' attention to survive. Infant-directed song may constitute a signal of that attention. In the rare genomic imprinting disorder Prader-Willi syndrome (PWS), typically paternally-expressed genes from chromosome 15q11–q13 are unexpressed, resulting in exaggeration of traits that reduce offspring investment demands on the mother. PWS may thus be associated with a distinctive musical phenotype. We report unusual responses to music in PWS. Subjects (N = 39) moved more during music listening, exhibited greater reductions in heart rate in response to music listening, and displayed a specific deficit in pitch discrimination ability relative to typically-developing adults and children (N = 589). Paternally-expressed genes from 15q11–q13, unexpressed in PWS, may thus increase demands for music and enhance perceptual sensitivity to music. These results implicate genomic imprinting in the psychology of music, informing theories of music's evolutionary history

Genomic imprinting is implicated in the psychology of music

Why do we sing to babies? Human infants are relatively altricial and need their parents' attention to survive. Infant-directed song may constitute a signal of that attention. In the rare genomic imprinting disorder Prader-Willi syndrome (PWS), typically paternally-expressed genes from chromosome 15q11–q13 are unexpressed, resulting in exaggeration of traits that reduce offspring investment demands on the mother. PWS may thus be associated with a distinctive musical phenotype. We report unusual responses to music in PWS. Subjects (N = 39) moved more during music listening, exhibited greater reductions in heart rate in response to music listening, and displayed a specific deficit in pitch discrimination ability relative to typically-developing adults and children (N = 589). Paternally-expressed genes from 15q11–q13, unexpressed in PWS, may thus increase demands for music and enhance perceptual sensitivity to music. These results implicate genomic imprinting in the psychology of music, informing theories of music's evolutionary history

Origins of music in credible signaling

How did music evolve? We show that prevailing views on the evolution of music — that music is a byproduct of other evolved faculties, that music evolved for social bonding, and that music evolved to signal mate quality — are incomplete or wrong. We argue instead that music evolved as a credible signal in at least two contexts: coalitional interactions and infant care. We suggest that basic features of music, including melody and rhythm, result from adaptations in the proper domain of human music, providing a foundation that cultural evolution shapes into its actual domain